Fluid flow control valve

Abstract

A valve for use e.g. as a pilot valve in an offshore water deluge fire fighting system has a ported cylindrical body and an elastomeric sleeve defining between them an annular passage for flow between the various ports. Selected ports can be closed by means of captive balls which are cammed out by a central spool to deform localized areas of the sleeve into sealing contact with the housing wall surrounding the port openings. In this way the moving parts of the valve are isolated from the fluid by the sleeve and problems of sticking, e.g. caused by salt deposits when used with seawater, are avoided. In another embodiment, a flat pad of elastomeric material is used to the same effect in a ported body defining a planar flow passage.

We claim: 
     
       1. A main fluid flow control valve of the kind comprising an inlet and outlet separated by an impervious central barrier on a pervious support structure; a flexible sleeve surrounding said structure; an annular control chamber surrounding said sleeve; and control means for controlling the admission and release of fluid to and from said control chamber, whereby the flexible sleeve is held in sealing contact with the barrier to prevent fluid flow from said inlet to said outlet or is released from the barrier to permit fluid flow from said inlet to said outlet, in dependence upon the volume of fluid within said control chamber; wherein said control means comprise a pilot valve comprising: a solid body having a surface which defines one boundary wall of a passage for fluid flow; an elastomeric member mounted with an exterior surface thereof facing but spaced from said solid body surface whereby to define another boundary wall of said passage; at least two spaced-apart ports opening into said passage through said solid body surface; at least one movable control element juxtaposed to the surface of said elastomeric member on its side opposite to said exterior surface; and a movable actuating member juxtaposed to said at least one control element and formed with at least one selected cam surface therefor; whereby movement of the actuating member is effective to displace said at least one control element against the elastomeric member, in a direction generally perpendicular to the movement of the actuating member and to the adjacent surface of the elastomeric member, thereby to deform at least one selected portion of the elastomeric member into sealing contact with the facing solid body surface so as to control intercommunication through said passage for fluid flow between said ports. 
     
     
       2. A valve according to claim 1 wherein the solid body defines a flat boundary wall of the aforesaid flow passage, the elastomeric member is a generally flat member disposed in parallel to said wall, and the actuating member is in the form of a spool with its axis disposed generally parallel to the plane of the elastomeric member. 
     
     
       3. A main valve according to claim 1 wherein the pilot valve has: an inlet port connected to the inlet of the main valve; an outlet port connected via an open/close valve to a region of lower fluid pressure than said inlet; and a control port connected to said control chamber; opening of said open/close valve when the main valve is closed being effective to permit fluid to flow out of said control chamber through the pilot valve to said region of lower fluid pressure, thereby opening the main valve. 
     
     
       4. A main valve according to claim 3 comprising conduit means bypassing the pilot valve to connect the inlet of the main valve to said control chamber; said conduit means including a second open/close valve operating in conjuction with the first-mentioned open/close valve so that as the first-mentioned valve opens the second valve closes and vice versa. 
     
     
       5. A main valve according to claim 3 wherein said open/close valve comprises a solid body having a surface which defines one boundary wall of a passage for fluid flow; an elastomeric member mounted with an exterior surfaces thereof facing but spaced from said solid body surface whereby to define another boundary wall of said passage; two spaced-apart ports opening into said passage through said solid body surface; at least one movable control element juxtaposed to the surface of said elastomeric member on its side opposite to said exterior surface; and a movable actuating member juxtaposed to said at least one control element and formed with at least one selected cam surface therefore; whereby movement of the actuating member is effective to displace the at least one said control element against the elastomeric member, in a direction generally perpendicular to the movement of the actuating member and to the adjacent surface of the elastomeric member, thereby to deform at least one selected portion of the elastomeric member into sealing contact with the facing solid body surface so as to control intercommunication through said passage for fluid flow between the said ports. 
     
     
       6. A main valve according to claim 3 wherein said actuating member is in the form of a spool having at least one respective land and groove to register with a respective said control element and configured such that: in a first position of the spool said inlet, outlet and control ports, of the pilot valve all intercommunicate through said passage; in a second successive position of the spool said inlet, outlet and control ports of the pilot valve are all isolated from one another, and in a successive third position of the spool said inlet and control ports of the pilot valve intercommunicate through said passage while said outlet port of the pilot valve is isolated from said inlet and control ports thereof. 
     
     
       7. A main valve according to claim 6 wherein said inlet and outlet ports of the pilot valve are spaced-apart longitudinally with respect to said solid body surface; first and second said control elements are located on said opposite side of the elastomeric member in register respectively with said inlet and outlet ports; and said actuating member is in the form of an axially moving spool having fist and second axially spaced grooves and first and second axially spaced lands joined respectively by first and second cam surfaces, a third cam surface of opposite slope to said first cam surface is provided to the opposite side of said first land, and said second land has a greater axial extend than said fist land; whereby in said first position of the spool said first and second control elements register respectively with said first and second grooves; in said second position of the spool said first and second control elements run up said first and second cam surfaces to register respectively with said first and second lands; and in said third position of the spool said first control element runs down said third cam surface while said second control element remains in register with said second land; and comprising additional flow restrictor means associated with said inlet port. 
     
     
       8. A main valve according to claim 6 wherein said spool of the pilot valve is connected to pressure-responsive means such that, in use, the position of the spool is controlled in response to the fluid pressure pertaining at the outlet of the main valve. 
     
     
       9. A main valve according to claim 8 wherein the position of said spool is controlled such that, in use: when the pressure pertaining at said outlet is at a selected level the spool is in its said second position; if the pressure pertaining at said outlet falls below said selected level the spool is moved towards its said first position; and if the pressure pertaining at said outlet rises above said selected level the spool is moved towards its said third position. 
     
     
       10. A fluid flow control valve comprising: a solid body having a surface which defines an outer cylindrical boundary wall of a passage for fluid flow; an elastomeric member in the form of a sleeve disposed coaxially within said body with an exterior surface thereof facing but spaced from said solid body surface whereby to define another boundary wall of said passage; first, second and third ports opening into said passage through said solid body surface; at least two movable control elements juxtaposed to the surface of said elastomeric member on its side opposite to said exterior surface; and a movable actuating member in the form of a spool juxtaposed to said control elements and extending coaxially through the elastomeric member; said spool being formed with at least one respective land and groove to register with respective said control elements whereby movement of the spool is effective to displace the said control elements generally radially against the elastomeric member thereby to deform selected portions thereof into sealing contact with the facing solid body surface so as to control intercommunication through said passage for fluid flow between said ports and such that: in a first position of the spool said first, second and third ports all intercommunicate through said passage; in a second successive position of the spool said first, second and third ports are all isolated from one another; and in a successive third position of the spool said first and third ports intercommunicate through said passage while said second port is isolated from said first and third ports. 
     
     
       11. A valve according the claim 10 wherein each aforesaid control element comprises a ball trapped in a respective bore formed in a housing member disposed between the spool and the elastomeric member, and is located to deform the elastomeric member into sealing contact with the solid body surface around the opening of a respective said port. 
     
     
       12. A valve according to claim 10 wherein said first and second ports are spaced-apart axially with respect to said outer cylindrical wall; first and second said control elements are located inwards of said sleeve in register respectively with said first and second ports; and said spool is provided with first and second axially spaced grooves and first and second axially spaced lands joined respectively by first and second cam surfaces, a third cam surface of opposite slope to said first cam surface is provided to the opposite side of said first land, and said second land has a greater axial extent than said first land; whereby in said first position of the spool said first and second control elements register respectively with said first and second grooves; in said second position of the spool said first and second control elements run up said first and second cam surfaces to register respectively with said first and second lands; and in said third position of the spool said first control element runs down said third cam surface while second control element remains in register with said second land. 
     
     
       13. A valve according to claim 10 having additional flow restrictor means associated with said first port.